System, device and method for storage device assisted low-bandwidth data repair

ABSTRACT

According to one general aspect, an apparatus may include a regeneration-code-aware (RCA) storage device configured to calculate at least one type of data regeneration code for data error correction. The RCA storage device may include a memory configured to store data in chunks which, in turn, comprise data blocks. The RCA storage device may include a processor configured to compute, when requested by an external host device, a data regeneration code based upon a selected number of data blocks. The RCA storage device may include an external interface configured to transmit the data regeneration code to the external host device.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/932,679, filed on Jul. 17, 2020, which is a continuation of U.S.patent application Ser. No. 16/103,907, filed on Aug. 14, 2018, nowissued as U.S. Pat. No. 10,719,397, which claims priority under 35U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 62/682,763,filed on Jun. 8, 2018. These earlier filed applications are herebyincorporated by reference.

TECHNICAL FIELD

This description relates to data storage, and more specifically to asystem, device and/or method for storage device assisted low-bandwidthdata repair.

BACKGROUND

In coding theory, an erasure code is a forward error correction (FEC)code under the assumption of bit erasures (rather than bit errors),which transforms a message of k symbols into a longer message (codeword) with n symbols such that the original message can be recoveredfrom a subset of the n symbols. The fraction r=k/n is called the coderate. The fraction k′/k, where k′ denotes the number of symbols requiredfor recovery, is called reception efficiency.

Regenerating codes address the issue of rebuilding (also calledrepairing) lost encoded fragments from existing encoded fragments. Inmore detail, regenerating codes' are a class of codes that aim to reducethe amount of download during repair, while retaining the storageefficiency of traditional maximum distance separable (MDS) code. Thisissue occurs in distributed storage systems where communication tomaintain encoded redundancy is a problem.

A distributed storage system is generally is a computer network whereinformation is stored on more than one node or device, often in areplicated fashion. It is often used to refer to either a distributeddatabase where users store information on a number of nodes, or acomputer network in which users store information on a number of peernetwork nodes. Distributed storage systems typically use an errordetection and correction technique. Some distributed storage system useforward error correction techniques to recover the original file, chunk,or blob when parts of that file are damaged or unavailable. Others tryagain to download that file from a different mirror.

SUMMARY

According to one general aspect, an apparatus may include aregeneration-code-aware (RCA) storage device configured to calculate atleast one type of data regeneration code for data error correction. TheRCA storage device may include a memory configured to store data inchunks which, in turn, comprise data blocks. The RCA storage device mayinclude a processor configured to compute, when requested by an externalhost device, a data regeneration code based upon a selected number ofdata blocks. The RCA storage device may include an external interfaceconfigured to transmit the data regeneration code to the external hostdevice.

According to another general aspect, a system may include a host deviceand a distributed storage system. The host device may be configured tostore data, as a plurality of chunks, amongst a distributed storagesystem, detect when at least one chunk is associated with an error, andin response to the error, reconstruct, via a data regenerationtechnique, the chunk associated with the error based, at least in part,upon the plurality of chunks of the data. The distributed storage systemmay include a plurality of storage devices, wherein each storage deviceis configured to store at least a respective chunk of the data, andwherein the plurality of storage devices includes at least oneregeneration-code-aware (RCA) storage device, wherein each RCA storagedevice is configured to internally calculate at least one type of dataregeneration code.

According to another general aspect, a system may include a host deviceconfigured to: store data, in a plurality of chunks, amongst a storagesystem, detect when at least one chunk is associated with an error, andin response to the error, correct, via a data regeneration technique,the error based, at least in part, upon the plurality of chunks of thedata. The system may include the storage system that includes aplurality of storage devices, wherein each storage device is configuredto store at least a respective chunk of the data, and wherein theplurality of storage devices includes at least oneregeneration-code-aware (RCA) storage device, wherein each RCA storagedevice is configured to internally calculate at least one type of dataregeneration code The RCA storage device may include a memory configuredto store data in chunks, wherein each chunk comprises data blocks, aprocessor configured to compute, when requested by the host device, adata regeneration code based upon a selected number of data blocks, acode memory configured to store a plurality of sets of instructions,wherein each set of instructions generates a different data regenerationcode, and an external interface configured to transmit the dataregeneration code to the host device.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

A system and/or method for data storage, and more specifically tostorage device assisted low-bandwidth data repair, substantially asshown in and/or described in connection with at least one of thefigures, as set forth more completely in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example embodiment of a system inaccordance with the disclosed subject matter.

FIG. 2A is a block diagram of an example embodiment of a system inaccordance with the disclosed subject matter.

FIG. 2B is a block diagram of an example embodiment of a system inaccordance with the disclosed subject matter.

FIG. 2C is a block diagram of an example embodiment of a system inaccordance with the disclosed subject matter.

FIG. 2D is a block diagram of an example embodiment of a system inaccordance with the disclosed subject matter.

FIG. 3 is a flowchart of an example embodiment of a technique inaccordance with the disclosed subject matter.

FIG. 4 is a schematic block diagram of an information processing systemthat may include devices formed according to principles of the disclosedsubject matter.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Various example embodiments will be described more fully hereinafterwith reference to the accompanying drawings, in which some exampleembodiments are shown. The present disclosed subject matter may,however, be embodied in many different forms and should not be construedas limited to the example embodiments set forth herein. Rather, theseexample embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the presentdisclosed subject matter to those skilled in the art. In the drawings,the sizes and relative sizes of layers and regions may be exaggeratedfor clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itmay be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on”, “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third, andso on may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer, orsection from another region, layer, or section. Thus, a first element,component, region, layer, or section discussed below could be termed asecond element, component, region, layer, or section without departingfrom the teachings of the present disclosed subject matter.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” may encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

Likewise, electrical terms, such as “high” “low”, “pull up”, “pulldown”, “1”, “0” and the like, may be used herein for ease of descriptionto describe a voltage level or current relative to other voltage levelsor to another element(s) or feature(s) as illustrated in the figures. Itwill be understood that the electrical relative terms are intended toencompass different reference voltages of the device in use or operationin addition to the voltages or currents depicted in the figures. Forexample, if the device or signals in the figures are inverted or useother reference voltages, currents, or charges, elements described as“high” or “pulled up” would then be “low” or “pulled down” compared tothe new reference voltage or current. Thus, the exemplary term “high”may encompass both a relatively low or high voltage or current. Thedevice may be otherwise based upon different electrical frames ofreference and the electrical relative descriptors used hereininterpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of thepresent disclosed subject matter. As used herein, the singular forms“a”, “an” and “the” are intended to include the plural forms as well,unless the context clearly indicates otherwise. It will be furtherunderstood that the terms “comprises” and/or “comprising,” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe present disclosed subject matter.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosed subject matterbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein.

Hereinafter, example embodiments will be explained in detail withreference to the accompanying drawings.

FIG. 1 is a block diagram of an example embodiment of a system 100 inaccordance with the disclosed subject matter. In the illustratedembodiment, the system 100 may include a distributed storage system 104that stores data across a plurality of nodes or storage devices.

Distributed storage systems are often used to provide large-scalereliability storage. Often this is accomplished by spreading redundancyor error correction (e.g., parity) across a large number of nodes orstorage devices. However, when a node or storage device goes off-line(e.g., due to a network error, hardware failure, etc.) the data becomesuspect as possible corrupt, or at least having a reduced level ofredundancy. The more distributed a storage system is the more frequentlythis occurs.

A number of techniques may be employed to protect against such anoccurrence (e.g., mirroring, Reed-Solomon encoding), but the disclosedsubject matter is focused on regeneration encoding. In such anembodiment, the missing piece of data (a chunk) is regenerated orreconstructed using a formula based upon the remaining pieces of data.

In the illustrated embodiment, the system 100 may include one or morehost devices 102 configured to manage the distributed storage system104. The host device 102 may include a computing device (e.g., computer,server, virtual machine) that reads and writes to and from the storagesystem 104. When an error (e.g., a missing chunk of data) occurs, thehost device 102 is generally responsible for detecting and, if possible,repairing the error.

In the illustrated embodiment, each data set 199 may be broken down orfragmented by the host device 102 into a plurality of smaller pieces ofdata or chunks 198. In the illustrated embodiment, the data 199 isdivided into chunks 198 D1, D2, D3, and D4. Further, in variousembodiments, the host device 102 may apply some form of redundancy tothe data chunks 198, such as parity chunks P1 and P2 (also numbered 198as they are also chunks).

In the parlance of the art, the number of original data chunks 198 (D1,D2, D3, and D4) are described as the variable K or k. Likewise, thenumber of redundant data chunks 198 (P1 and P2) are described as thevariable R or r. Such that the total number of chunks 198 is K+R. In theillustrated embodiment, K equal 4, R equals 2, and K+R equals 6;although, it is understood that the above is merely an illustrativeexample to which the disclosed subject matter is not limited.

In the illustrated embodiment, the host device 102 stores each of thesechunks 198 (both original and redundant) on respective nodes or storagedevices of the storage system 104.

In the illustrated embodiment, the storage device 114 stores chunk 198D1, the storage device 114-1 stores chunk 198 D2, the storage device 116stores chunk 198 D3, the storage device 114-2 stores chunk 198 D$, thestorage device 116-1 stores chunk 198 P1, and the storage device 114-3stores chunk 198 P2. In various embodiments, the number of storagedevices 114/116 may not equal the number of chunks 198.

In various embodiments, a chunk 198 may go missing (e.g., network orhardware failure) or may otherwise be associated with an error. In theillustrated embodiment, let us say chunk 198 D3 (and storage device 116)suddenly become unavailable. The host device 102 upon detecting theerror, may attempt to recreate the chunk 198 D3 or otherwise correct theerror.

In such an embodiment, if one chunk fails (e.g., chunk 198 D3), andthere were K (e.g., 4) total chunks in the original data 199, at-least K(e.g., 4) nodes or storage devices 114/116 have to send information tothe host device 102 to recover of the failed chunk (e.g., chunk 198 D3).Note, these K (e.g., 4) chunks may come from any of the K+R (e.g., 6)chunks. For example, chunks 198 D1, D2, D4, and P1 may be used torecreate chunk 198 D3.

Regeneration codes reduces the repair bandwidth by sending less than afull chunk size information from D nodes, where typically D>K. In otherwords, by use of a clever formula, the host device 102 may be able torecreate the missing chunk 198 D3, by using, not the full chunks 198 D1,D2, D4, and P1, but by using only a part of the 198 D1, D2, D4, P1, andP2. A regeneration code generally takes information from more storagedevice 114/116, but it takes less information from each storage device114/116 than a non-regenerative code would.

For example, if 6 chunks of data were used (K=6) and 6 chunks ofredundancy were used (R=6 and K+R=12) and each chunk was 16 MB in size,the standard Reed-Solomon (RS) error correction encoding scheme wouldrequire that 6 (K) 16 MB chunks be sent to the host device or 96 MB ofdata be transmitted to correct a missing 16 MB chunk. Conversely, if aregenerative technique was used, portions of all 12 (K+R or D, in thiscase) chunks would be read, but that since only a portion of each chunkwas used (e.g., 2.7 MB) the total amount transmitted to the host devicemay be lower (e.g., 29.7 MB).

Often regeneration codes have a storage and bandwidth tradeoff. invarious embodiments, In general, there are two classes or groups ofregenerative codes. If storage overhead is minimal, they are calledMinimum Storage Regeneration (MSR) codes. If repair bandwidth is minimalfor added storage overhead, they are called Minimum BandwidthRegeneration (MBR) codes. Within these broad categories, variousspecific techniques or formulas may be employed to perform theregenerative codes. It is understood that the above are merely a fewillustrative examples to which the disclosed subject matter is notlimited.

Returning to FIG. 1 , In the illustrated embodiment, the storage system1-4 may include a plurality of storage devices 114/116. Each storagedevice 114/116 may be configured to store data, in chunks or otherwise.In the illustrated embodiment, the storage devices 114 may be relativelytraditional storage devices, such as hard drives, solid state drives, oreven volatile memories.

However, in the illustrated embodiment, the storage system 104 may alsoinclude regeneration-code-aware (RCA) storage devices 116. In such anembodiment, unlike traditional or non-RCA storage devices 114 the RCAstorage devices 116 may be configured to and include components thatallow them to aid in the calculation of a data regeneration code. Asdiscussed in more detail later, the host device 102 may be able todynamically offload some of the computing of the data regeneration codeto the RCA storage device 116. In various embodiments, this may reducethe amount of messages sent back-and-forth between the host device 102and storage system 104, the amount of data transferred between the hostdevice 102 and the storage system 104, and/or the computing load on thehost device 102. It is understood that the above are merely a fewillustrative examples to which the disclosed subject matter is notlimited.

In various embodiments, the RCA storage devices 116 may be programmable,such that the host device 102 may be able to update them with the latestor a desired regeneration code formula or technique. In such anembodiment, the RCA storage devices 116 may be able to store multipleregeneration techniques and have one of them be dynamically orsemi-statically selected by the host device 102. In such an embodiment,the host device 102 may select which if the regeneration techniquesshould be employed at a given moment.

In various embodiments, the storage system 104 may be distributed. Insuch an embodiment, the storage devices 114/116 may be physically remotefrom each other and communicate via a network protocol. In anotherembodiment, storage devices 114/116 may be relatively localized (e.g.,in a server farm or the same building) but still communicate via anetwork protocol. In yet another embodiment, the storage system 104 maynot be distributed. In such an embodiment, the disclosed subject mattermay be employed for local device (e.g., same machine) that does not usea network protocol (e.g., USB, SATA). It is understood that the aboveare merely a few illustrative examples to which the disclosed subjectmatter is not limited.

In various embodiments, the regeneration-code-aware (RCA) storage device116 may include the capability to calculate different types or versionsof regeneration codes. In such an embodiment, the desired type orversion of regeneration code may be chosen dynamically by the hostdevice 102. In some embodiments, the RCA storage deice 116 may becapable of splitting data into smaller blocks or packets, calculating anerasure code or portion thereof, processing data chunk(s) for repair ofanother failed chunk, and so on.

In various embodiments, a communications protocol may exist between thehost device 102 and the RCA storage device 116 to implement datareliability using any regeneration codes or techniques. In such anembodiment, the protocol may allow for selecting a regenerationtechnique, passing inputs, directing the operation of the desiretechnique, and retrieving any outputs. In some embodiments, the protocolmay define host behavior when it works in a mixed environment containingboth RCA and non-RCA storage devices 116/114 and how to interact withboth. In various embodiments, the host system 102 may use the protocolto setup an RCA storage device 116, encode/read/write user data and tooffload the computation during data repair, to reduce the data trafficand accelerate computation and rebuild the original data using thecapabilities of the RCA storage device 116.

FIG. 2A is a block diagram of an example embodiment of a system 201 inaccordance with the disclosed subject matter. In the illustratedembodiment, the system 201 shows an interaction between the host device210 and a storage device 212 to compute a first kind (Type 1)regeneration code. In various embodiments, the system 201 may beemployed for traditional or non-RCA storage devices, and even for RCAstorage devices if their RCA functions are not employed.

In the illustrated embodiment, the system 201 may include a host device210 and a storage device 212. In such an embodiment, the host device 210may include a processor 232 to execute instructions and performcomputations, a memory 234 to store, at least temporarily data or piecesthereof, and an interface 236 to communicate with the storage device 212or more generally the storage system (not shown). In such an embodiment,the storage device 212 may include a memory 224 configured to storedata. In various embodiments, this memory 224 may be non-volatile orvolatile.

In the illustrated embodiment, the chunks 214 are sub-divided intoblocks 216. In such an embodiment, the host device may take the blocks216 from one or more chunks 214 stored on the storage device 212 (andfrom K−1 chunks stored on other storage devices) and compute aregeneration code 218 (R1).

In such a regeneration code technique (Type 1), blocks 216 are composedof smaller packets (not shown). For each node or storage device 212, thehost device 210 calculates, using various packets, a parity packet orregeneration code 218. Each storage device's respective regenerationcode 218 is used to reconstruct the missing or errored chunk. Ingeneral, for Type 1 regeneration code techniques the computation islinear and depends on the chunk that failed. The amount of data sentback depends on the sub-packetization level and the function.

In the illustrated embodiment, once the host device 210 detects an errorit may transmit a data read request or command 242A to the storagedevice 212. The data read command 242A may include which chunk 214 is tobe read (e.g., chunk 214C). The storage device 212 then transmit thedesired chunk 214 to the host device 210, via the data read response ormessage 244A. In various embodiments, this may all be done using atraditional host-to-storage device 212 protocol (e.g., SATA).

Upon receipt of the desired chunk 214C, by the interface 236 the hostdevice 210 may store the chunk 214C or blocks 216 in the memory 234. Theprocessor 232 may then perform the desired regeneration code technique287. While the regeneration code technique 287 is illustrated as asimple addition or Boolean XORing, is understood that the above aremerely a few illustrative examples to which the disclosed subject matteris not limited. As described above, in various embodiments, this mayinclude sub-dividing the blocks 216 into smaller packets. Theregeneration code technique 287 may compute or generate the regenerationcode 218 (R1) which is then, with the regeneration codes associated withother chunks or storage devices, may be used to reconstruct or repairthe errored chunk.

FIG. 2B is a block diagram of an example embodiment of a system 203 inaccordance with the disclosed subject matter. In the illustratedembodiment, the system 203 shows an interaction between the host device210 and an RCA storage device 252 to compute a first kind (Type 1)regeneration code. In various embodiments, the system 203 may only beemployed RCA storage devices and not for a non-RCA storage device.

In the illustrated embodiment, the system 201 may include a host device210 and an RCA storage device 252. In such an embodiment, the hostdevice 210 may include a processor 232 to execute instructions andperform computations, a memory 234 to store, at least temporarily dataor pieces thereof, and an interface 236 to communicate with the storagedevice 212 or more generally the storage system (not shown).

In such an embodiment, the RCA storage device 252 may include a memory224 configured to store data. In various embodiments, this memory 224may be non-volatile or volatile. Further, in various embodiments, theRCA storage device 252 may include a processor 222 configured tocompute, when requested by the host device 210 (which is generallyexternal to the storage devices), a data regeneration code 218 basedupon a selected number of data blocks 216. In various embodiments, theprocessor 222 may include a programmable gate array (e.g., FGPA), agraphic processor unit (GPU), a general purpose processor (e.g., CPU), acontroller processor, or a system-on-a-chip (SoC). It is understood thatthe above are merely a few illustrative examples to which the disclosedsubject matter is not limited. The RCA storage device 252 may include acode memory 228 configured to store a plurality of sets of instructions229, wherein each set of instructions 229 generate a different dataregeneration code or instructions on how to perform a differentregeneration code technique. In various embodiments, the set ofinstructions 229 may be pre-configured into the storage device 252 ordynamically added/adjusted during run time (e.g., by the host device210), or a combination thereof. The RCA storage device 252 may includean external interface 226 configured to communicate with at least thehost device 210.

In the illustrated embodiment, the host device 210 may determine if thestorage device 252 is capable of internally computing a dataregeneration code or, in general, is an RCA storage device. If so, thehost device 210 may determine if the RCA storage device 252 may performthe desired regeneration code technique or if it may be programmed to doso (via the code memory 228). If not, the technique shown in FIG. 2A maybe employed.

If the RCA storage device 252 is capable of performing the desiredregeneration code technique, the host device 210 may issue a Read forRepair command 242B. In various embodiments, the Read for Repair command242B may include or indicate one or more of the following: an indicationof the desired regeneration or repair technique, the desired packet orblock size, any parameters for the desired regeneration or repairtechnique, the data or chunk address, and the failed chunk number. It isunderstood that the above are merely a few illustrative examples towhich the disclosed subject matter is not limited.

In response to the command 242B, the processor 222 may retrieve thedesired blocks 216 or chunk 214C. The processor 222 may also retrievethe set of instructions 229 associated with the desired regeneration orrepair technique. The processor 222 may perform the desired regenerationtechnique 287 and compute the data regeneration code (DRC) 218 (R1).

The RCA storage device 252 may then transmit (message 244B), via theinterface 226, the data regeneration code 218 (R1) to the host device210. In such an embodiment, the data regeneration code 218 (R1) may havea smaller size or consume less bandwidth than the data transmitted viamessage 244A of FIG. 2A.

In the illustrated embodiment, the messages 242B and 244B may require adifferent protocol than that used for messages 242A and 244A. While themessages 242A and 244A may be allowed by a traditional storage deviceprotocol, the messages 242B and 244B may require additional anddifferent information and hence a new messaging protocol or at least newcommands.

In the illustrated embodiment, the host device 210 may then use the dataregeneration code 218 (R1), along with any additional data regenerationcodes provided by other RCA storage devices (not shown) or generated bythe host device 210 itself, to recreate the errored chunk of data.

FIG. 2C is a block diagram of an example embodiment of a system 205 inaccordance with the disclosed subject matter. In the illustratedembodiment, the system 205 shows an interaction between the host device210 and a storage device 212 to compute a second kind (Type 2)regeneration code. In various embodiments, the system 205 may beemployed for traditional or non-RCA storage devices, and even for RCAstorage devices if their RCA functions are not employed.

In the illustrated embodiment, the system 205 may include the hostdevice 210 and storage device 212. Both the host device 210 and storagedevice 212 may include the components illustrated and described above.

In such a regeneration code technique (Type 2), data regeneration codesare computed such that fewer packets (not shown) or blocks 216 have tobe read. However, this often means that the desired blocks 216 orpackets are known in full ahead of time but are requested piecemeal asthe computation progresses. While this kind of regeneration techniquereduces both the network bandwidth and data read theoretically, itconverts one large read into multiple smaller reads, which is not goodfor performance.

In the illustrated embodiment, the host device, using portion 288 of thedesired regeneration technique computes that if block E1 is associatedwith an error, then blocks B1 and B3 (or packets thereof) will be neededto fix the errored block E1. In such an embodiment, once the host device210 detects that block B1 is needed it may transmit a data read requestor command 242C to the storage device 212. The data read command 242Cmay indicate which block 216 is to be read (e.g., block B1). The storagedevice 212 then transmits the desired block 216 B1 to the host device210, via the data read response or message 244C. In various embodiments,this may all be done using a traditional host-to-storage device 212protocol (e.g., SATA).

In such an embodiment, once the host device 210 detects that block B3 isneeded it may transmit a data read request or command 246C to thestorage device 212. This is typically done as a second data request,separate from the one requesting block B1. The data read command 246Cmay indicate which block 216 is to be read (e.g., now block B3). Thestorage device 212 then transmits the desired block 216 B3 to the hostdevice 210, via the data read response or message 248C. In variousembodiments, this may all be done using a traditional host-to-storagedevice 212 protocol (e.g., SATA).

Upon receipt of the desired blocks 216, by the interface 236 the hostdevice 210 may store the blocks 216 in the memory 234. The processor 232may then perform the desired regeneration code technique (shown by theportion 289). The regeneration code technique (or portion 289) maycompute or generate the regeneration code 219 (R1) which is then, withthe regeneration codes associated with other chunks or storage devices,may be used to reconstruct or repair the errored chunk.

FIG. 2D is a block diagram of an example embodiment of a system 207 inaccordance with the disclosed subject matter. In the illustratedembodiment, the system 207 shows an interaction between the host device210 and an RCA storage device 252 to compute a first kind (Type 2) ofregeneration code. In various embodiments, the system 207 may only beemployed RCA storage devices and not for a non-RCA storage device.

In the illustrated embodiment, the system 207 may include the hostdevice 210 and storage device 252. Both the host device 210 and storagedevice 252 may include the components illustrated and described above.

In the illustrated embodiment, the host device 210 may determine if thestorage device 252 is capable of internally computing a dataregeneration code or, in general, is an RCA storage device. If so, thehost device 210 may determine if the RCA storage device 252 may performthe desired regeneration code technique or if it may be programmed to doso (via the code memory 228). If not, the technique shown in FIG. 2C maybe employed.

If the RCA storage device 252 is capable of performing the desiredregeneration code technique, the host device 210 may issue a Read forRepair command 242D. In various embodiments, the Read for Repair command242D may include or indicate one or more of the following: an indicationof the desired regeneration or repair technique, the desired packet orblock size, any parameters for the desired regeneration or repairtechnique, the data or chunk address, and the failed chunk number (e.g.,block E1). It is understood that the above are merely a few illustrativeexamples to which the disclosed subject matter is not limited.

In response to the command 242B, the processor 222 may retrieve the setof instructions 229 associated with the desired regeneration or repairtechnique. The processor 222 may perform the desired regenerationtechnique or portion 288 thereof. In such an embodiment, the processor22 may compute that the desired blocks are B1 and B3. In such anembodiment, these bocks B1 and B2 may be included in the dataregeneration code computed by the RCA storage device 252. In such anembodiment, these blocks may be considered only part of the response tothe Read for Repair command 242D.

The RCA storage device 252 may then transmit (message 244D), via theinterface 226, the desired blocks B1 and B3 to the host device 210. Insuch an embodiment, the data regeneration code or the desired blocks B1and B3 may have a smaller size or consume less bandwidth or at leastinclude less message and hence less overhead than the data transmittedvia messages 244C and 248C of FIG. 2C.

In the illustrated embodiment, the messages 242D and 244D may require adifferent protocol than that used for messages 242C, 244C, 246C, and248C. While the messages 242C, 244C, 246C, and 248C may be allowed by atraditional storage device protocol, the messages 242D and 244D mayrequire additional and different information and hence a new messagingprotocol or at least new commands.

In the illustrated embodiment, the host device 210 may then use the dataregeneration code, or blocks B1 and B3, along with any additional dataregeneration codes or data provided by other RCA storage devices (notshown) or generated by the host device 210 itself, to recreate theerrored data (E1).

FIG. 3 is a flowchart of an example embodiment of a technique 300 inaccordance with the disclosed subject matter. In various embodiments,the technique 300 may be used or produced by the systems such as thoseof FIGS. 1, 2A, 2B, 2C, and 2D. Although, it is understood that theabove are merely a few illustrative examples to which the disclosedsubject matter is not limited. It is understood that the disclosedsubject matter is not limited to the ordering of or number of actionsillustrated by technique 300.

In the illustrated embodiment, for the sake of simplicity, the technique300 illustrates an example in which all the devices of the storagesystem are either RCA storage devices or non-RCA storage devices (i.e. ahomogeneous storage system). For mixed or heterogeneous storage systems,one skilled in the art will understand how the simplified technique 300may be expanded to apply on an individual storage device basis.

Block 302 illustrates that, in one embodiment, an error associated witha chunk of data may be detected. In various embodiments, one or more ofthe action(s) illustrated by this Block may be performed by theapparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D, as described above.

Block 304 illustrates that, in one embodiment, a determine may be madeas to whether the data regeneration code (DRC) will be computed by thehost device or by the respective RCA storage devices, as describedabove. In various embodiments, one or more of the action(s) illustratedby this Block may be performed by the apparatuses or systems of FIG. 1,2A, 2B, 2C, or 2D, as described above.

Block 306 illustrates that, in one embodiment, if the RCD is to becomputed by the host in a more traditional way, a determine may be madeas to whether there is enough existing data to compute the RCD, asdescribed above. In one such embodiment, this may include determining ifK chunks are available out of the K+R data chunks. In variousembodiments, one or more of the action(s) illustrated by this Block maybe performed by the apparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D,as described above.

Block 399 illustrates that, in one embodiment, if not enough error-freechunks exist to compute the RCD that some other form of error handling,beyond the recreation of the errored chunk of data may occur. In variousembodiments, this may simply be the reporting that data is corrupt orunavailable. In various embodiments, one or more of the action(s)illustrated by this Block may be performed by the apparatuses or systemsof FIG. 1, 2A, 2B, 2C, or 2D, as described above.

Block 308 illustrates that, in one embodiment, the required number ofchunks (e.g., K chunks) may be read from various (e.g., K+R) storagedevices, as described above. In various embodiments, this may simply bethe reporting that data is corrupt or unavailable. In variousembodiments, one or more of the action(s) illustrated by this Block maybe performed by the apparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D,as described above.

Block 310 illustrates that, in one embodiment, the host device mayreconstruct or recreate the errored chunk using the error-free chunks(e.g., K chunks), as described above. In various embodiments, this maysimply be the reporting that data is corrupt or unavailable. In variousembodiments, one or more of the action(s) illustrated by this Block maybe performed by the apparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D,as described above.

Block 350 illustrates that, in one embodiment, a determination may bemade if there are enough error-free chunks (e.g., D chunks) to computethe DRC, as described above. If not, in various embodiments, thetechnique 300 may resort to attempting the non-RCA device path startingwith Block 306. Otherwise, the technique 300 may continue to Block 352.In various embodiments, this may simply be the reporting that data iscorrupt or unavailable. In various embodiments, one or more of theaction(s) illustrated by this Block may be performed by the apparatusesor systems of FIG. 1, 2A, 2B, 2C, or 2D, as described above.

Block 352 illustrates that, in one embodiment, a read for repair commandmay be issued to the required number (e.g., D) of the total (e.g., K+R)storage devices, as described above. In various embodiments, one or moreof the action(s) illustrated by this Block may be performed by theapparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D, as described above.

Block 354 illustrates that, in one embodiment, a determination may bemade as to which of a plurality of versions or types of DRC techniquesare to be used, as described above. In the illustrated embodiment, theversions or types of DRC techniques are generalized into the Type 1 and2 techniques described above, but it is understood that these types aremerely a few illustrative examples to which the disclosed subject matteris not limited, and furthermore within those broad types many sub-typesmay exist, as described above. In various embodiments, one or more ofthe action(s) illustrated by this Block may be performed by theapparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D, as described above.

Block 356 illustrates that, in one embodiment, if the Type 1 DRCtechnique is selected, the repair function may be applied to the chunkswithin the RCA storage device, as described above. In variousembodiments, one or more of the action(s) illustrated by this Block maybe performed by the apparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D,as described above.

Block 358 illustrates that, in one embodiment, if the Type 2 DRCtechnique is selected, the blocks (or other sub-portions such aspackets) needed for repair may be calculated, as described above. Invarious embodiments, one or more of the action(s) illustrated by thisBlock may be performed by the apparatuses or systems of FIG. 1, 2A, 2B,2C, or 2D, as described above.

Block 360 illustrates that, in one embodiment, once the DRC or theneeded blocks are computed, the DRC or blocks may be transmitted to thehost device, as described above. In various embodiments, this mayinclude a smaller size of data or smaller number of messages than thenon-RCA path, as described above. In various embodiments, one or more ofthe action(s) illustrated by this Block may be performed by theapparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D, as described above.

Block 362 illustrates that, in one embodiment, the host device mayreconstruct or recreate the errored chunk using the DRC or returnedblocks, as described above. In various embodiments, this may simply bethe reporting that data is corrupt or unavailable. In variousembodiments, one or more of the action(s) illustrated by this Block maybe performed by the apparatuses or systems of FIG. 1, 2A, 2B, 2C, or 2D,as described above.

FIG. 4 is a schematic block diagram of an information processing system400, which may include semiconductor devices formed according toprinciples of the disclosed subject matter.

Referring to FIG. 4 , an information processing system 400 may includeone or more of devices constructed according to the principles of thedisclosed subject matter. In another embodiment, the informationprocessing system 400 may employ or execute one or more techniquesaccording to the principles of the disclosed subject matter.

In various embodiments, the information processing system 400 mayinclude a computing device, such as, for example, a laptop, desktop,workstation, server, blade server, personal digital assistant,smartphone, tablet, and other appropriate computers or a virtual machineor virtual computing device thereof. In various embodiments, theinformation processing system 400 may be used by a user (not shown).

The information processing system 400 according to the disclosed subjectmatter may further include a central processing unit (CPU), logic, orprocessor 410. In some embodiments, the processor 410 may include one ormore functional unit blocks (FUBs) or combinational logic blocks (CLBs)415. In such an embodiment, a combinational logic block may includevarious Boolean logic operations (e.g., NAND, NOR, NOT, XOR),stabilizing logic devices (e.g., flip-flops, latches), other logicdevices, or a combination thereof. These combinational logic operationsmay be configured in simple or complex fashion to process input signalsto achieve a desired result. It is understood that while a fewillustrative examples of synchronous combinational logic operations aredescribed, the disclosed subject matter is not so limited and mayinclude asynchronous operations, or a mixture thereof. In oneembodiment, the combinational logic operations may comprise a pluralityof complementary metal oxide semiconductors (CMOS) transistors. Invarious embodiments, these CMOS transistors may be arranged into gatesthat perform the logical operations; although it is understood thatother technologies may be used and are within the scope of the disclosedsubject matter.

The information processing system 400 according to the disclosed subjectmatter may further include a volatile memory 420 (e.g., a Random AccessMemory (RAM)). The information processing system 400 according to thedisclosed subject matter may further include a non-volatile memory 430(e.g., a hard drive, an optical memory, a NAND or Flash memory). In someembodiments, either the volatile memory 420, the non-volatile memory430, or a combination or portions thereof may be referred to as a“storage medium”. In various embodiments, the volatile memory 420 and/orthe non-volatile memory 430 may be configured to store data in asemi-permanent or substantially permanent form.

In various embodiments, the information processing system 400 mayinclude one or more network interfaces 440 configured to allow theinformation processing system 400 to be part of and communicate via acommunications network. Examples of a Wi-Fi protocol may include, butare not limited to, Institute of Electrical and Electronics Engineers(IEEE) 802.11g, IEEE 802.11n. Examples of a cellular protocol mayinclude, but are not limited to: IEEE 802.16m (a.k.a. Wireless-MAN(Metropolitan Area Network) Advanced, Long Term Evolution (LTE)Advanced, Enhanced Data rates for GSM (Global System for MobileCommunications) Evolution (EDGE), Evolved High-Speed Packet Access(HSPA+). Examples of a wired protocol may include, but are not limitedto, IEEE 802.3 (a.k.a. Ethernet), Fibre Channel, Power Linecommunication (e.g., HomePlug, IEEE 1901). It is understood that theabove are merely a few illustrative examples to which the disclosedsubject matter is not limited.

The information processing system 400 according to the disclosed subjectmatter may further include a user interface unit 450 (e.g., a displayadapter, a haptic interface, a human interface device). In variousembodiments, this user interface unit 450 may be configured to eitherreceive input from a user and/or provide output to a user. Other kindsof devices may be used to provide for interaction with a user as well;for example, feedback provided to the user may be any form of sensoryfeedback, e.g., visual feedback, auditory feedback, or tactile feedback;and input from the user may be received in any form, including acoustic,speech, or tactile input.

In various embodiments, the information processing system 400 mayinclude one or more other devices or hardware components 460 (e.g., adisplay or monitor, a keyboard, a mouse, a camera, a fingerprint reader,a video processor). It is understood that the above are merely a fewillustrative examples to which the disclosed subject matter is notlimited.

The information processing system 400 according to the disclosed subjectmatter may further include one or more system buses 405. In such anembodiment, the system bus 405 may be configured to communicativelycouple the processor 410, the volatile memory 420, the non-volatilememory 430, the network interface 440, the user interface unit 450, andone or more hardware components 460. Data processed by the processor 410or data inputted from outside of the non-volatile memory 430 may bestored in either the non-volatile memory 430 or the volatile memory 420.

In various embodiments, the information processing system 400 mayinclude or execute one or more software components 470. In someembodiments, the software components 470 may include an operating system(OS) and/or an application. In some embodiments, the OS may beconfigured to provide one or more services to an application and manageor act as an intermediary between the application and the varioushardware components (e.g., the processor 410, a network interface 440)of the information processing system 400. In such an embodiment, theinformation processing system 400 may include one or more nativeapplications, which may be installed locally (e.g., within thenon-volatile memory 430) and configured to be executed directly by theprocessor 410 and directly interact with the OS. In such an embodiment,the native applications may include pre-compiled machine executablecode. In some embodiments, the native applications may include a scriptinterpreter (e.g., C shell (csh), AppleScript, AutoHotkey) or a virtualexecution machine (VM) (e.g., the Java Virtual Machine, the MicrosoftCommon Language Runtime) that are configured to translate source orobject code into executable code which is then executed by the processor410.

The semiconductor devices described above may be encapsulated usingvarious packaging techniques. For example, semiconductor devicesconstructed according to principles of the disclosed subject matter maybe encapsulated using any one of a package on package (POP) technique, aball grid arrays (BGAs) technique, a chip scale packages (CSPs)technique, a plastic leaded chip carrier (PLCC) technique, a plasticdual in-line package (PDIP) technique, a die in waffle pack technique, adie in wafer form technique, a chip on board (COB) technique, a ceramicdual in-line package (CERDIP) technique, a plastic metric quad flatpackage (PMQFP) technique, a plastic quad flat package (PQFP) technique,a small outline package (SOIC) technique, a shrink small outline package(SSOP) technique, a thin small outline package (TSOP) technique, a thinquad flat package (TQFP) technique, a system in package (SIP) technique,a multi-chip package (MCP) technique, a wafer-level fabricated package(WFP) technique, a wafer-level processed stack package (WSP) technique,or other technique as will be known to those skilled in the art.

Method steps may be performed by one or more programmable processorsexecuting a computer program to perform functions by operating on inputdata and generating output. Method steps also may be performed by, andan apparatus may be implemented as, special purpose logic circuitry,e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

In various embodiments, a computer readable medium may includeinstructions that, when executed, cause a device to perform at least aportion of the method steps. In some embodiments, the computer readablemedium may be included in a magnetic medium, optical medium, othermedium, or a combination thereof (e.g., CD-ROM, hard drive, a read-onlymemory, a flash drive). In such an embodiment, the computer readablemedium may be a tangibly and non-transitorily embodied article ofmanufacture.

While the principles of the disclosed subject matter have been describedwith reference to example embodiments, it will be apparent to thoseskilled in the art that various changes and modifications may be madethereto without departing from the spirit and scope of these disclosedconcepts. Therefore, it should be understood that the above embodimentsare not limiting, but are illustrative only. Thus, the scope of thedisclosed concepts are to be determined by the broadest permissibleinterpretation of the following claims and their equivalents, and shouldnot be restricted or limited by the foregoing description. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the scope of theembodiments.

What is claimed is:
 1. An apparatus comprising: a storage deviceconfigured to calculate at least one type of information for errorcorrection; the storage device comprising: a memory configured to storedata in chunks comprising data blocks; a processor configured tocompute, based on a request associated with a device, information basedupon the data blocks; and an interface configured to: transmit theinformation to the device, and receive a command from the device thatconfigures the processor to determine the information.